| 摘要 |
PURPOSE:To contrive an improvement in air flow resisting properties in a low combustion region while an improvement in thermal efficiency is contrived, by providing an electric control part controlling a variable gas throttle, a variable air throttle and an adjusting device of a gas quantity which have been constituted so that a throttle opening can be changed variably when a quantity of combustion comes to a predetermined value. CONSTITUTION:An adjusting device 2 of gas quantity, a variable gas throttle 3 and a variable air throttle 6 are controlled by an electric control part 13. As a primary excess air ratio is predetermined and controlled by a differential pressure detecting device 9 so that an expression of PG=PA is given due to a matter that though control pressure PG comes to a little higher side within a region from a predetermined value to the minimum quantity of combustion as the variable throttle 6 is throttled at the same time, a quantity of secondary air is increased and an excess air ratio (m) can be controlled at a little higher side. Within a region from the maximum nominal quantity of combustion to a predetermined value (q) an air quantity can be controlled variably in proportion to the gas quantity while openings of the variable gas throttle and the variable air throttle are kept fixed to a larger side and within this region the excess air ratio (m) can be increased whether a fixed error of the differential pressure detecting device 9 is plus or minus. |
